FR3000535A1 - Fixing device for irreversible fixing of valve stem to actuator, has deformable element located at end of valve stem, so as to deform during fixing of valve stem to actuator, where deformation of deformable element is irreversible - Google Patents

Abstract

The device has a male screw (25) and a female screw (27) for connecting a valve stem (20) to an actuator (22). A deformable element (24) located at an end of the valve stem deforms during fixing of the valve stem to the actuator, where the deformation of the deformable element is irreversible. A punch (28) is located at the bottom of a cavity (26) formed in a relief part (30) of the actuator. A maintaining element (29) of the deformable element maintains the deformable element after the deformation of the deformable element.

Description

The present invention mainly relates to the automotive industry and more particularly to a device for fixing, more particularly irreversibly, a valve stem to an actuator. The valves are important components of a heat engine since they ensure the communication of the combustion chambers with the intake ducts fresh air mixed or not with a fuel and with the exhaust ducts burnt gases . There are several types of valves but the ones that are most often used are so-called "stem valves" or "tulip" valves. A stem valve consists of a head, which can rest on a seat of the combustion chamber to close or open the chamber, a rod having generally a cylindrical shape, said rod ending in a tail at the opposite end to the head. Conventionally, the valves are opened using an actuator comprising a camshaft and are biased in the closed position by return springs. However, there is another type of valves that are no longer actuated by cams but are operated by electromagnetic actuators. The engines using this new technology are called "cameless" (in French). Each valve is individually controlled by a computer, which allows greater control flexibility. Figures 1a and 1b schematically illustrate this type of valve. In these figures, the actuator 10 comprises two excitation coils 11a and 11b, integral with the cylinder head 12 of the engine. Between the coils 11 is placed a movable magnet 13 (ferrite). The moving magnet and its support constitute the movable part of the actuator. The coils 11 are powered by a source of electrical energy (not shown) controlled by a computer. The valve 14 comprises a head 15 and a rod 16 ending in a tail 17. The head 15 cooperates with a seat 18 of the cylinder head 12. The tail 17 is secured to the movable magnet 13 by means of the fixing device 19 which is the object of the present invention. One of the difficulties encountered in the design and manufacture of the valves generally comes from the lack of available space 5 for housing in the cylinder head the valves, the actuator and the link between the actuator and the valve tails. It is therefore important to try to reduce as much as possible the congestion of this link. This is particularly the case for the electromagnetic valves because the fastening device 19 between the movable magnet 13 and the tail 17 is generally more bulky than for the valves controlled by means of cams. Many solutions have already been proposed for attaching a valve to an actuator. For example, EP1421263B1 relates to a connection between a valve and an actuator, but the mounting of this connection is reversible and is not as easy as that proposed by the invention. There may also be mentioned patents EP1134362B1and DE19811779C1 or US2006 / 0231783A1 which relate to connections between a valve and an actuator. However, the links described in the documents are relatively complex and / or cumbersome. The present invention proposes a loosely fitting fastening device which fits well with the actuator and which allows an axial assembly of the valve, that is to say an assembly along the longitudinal axis of the valve. . In addition, the attachment is irreversible in that it can be dismantled only by breaking a part (a fuse piece for example). [0009] More specifically, the invention relates to a device for irreversibly fixing a valve stem to the movable part of an actuator, the device comprising means for screwing said tail to said actuator and deformable means by screwing. said tail, the deformation of said means making it impossible to attach said tail to said actuator. Said deformable means may comprise a deformable element, a deformation member of said element and a holding element of said deformable element to maintain said element after its deformation. According to one embodiment, said actuator comprises a raised portion for receiving the end of said tail, said deformable member is hollow (at least in part), said means for screwing said tail to said actuator comprise a step of screw belonging to said tail and a screw thread belonging to said raised portion, said screw threads being intended to cooperate with each other, said deformation member comprises a punch and said holding member comprises a groove, said punch spreading the walls of said deformable member into said groove when said tail is screwed to said actuator. According to an alternative embodiment: - said deformable element is located at the end of said tail, - said raised element comprises a cavity, - said punch is located at the bottom of said cavity, - said groove is located in said cavity and - the thread of said tail is a male thread, the thread of said cavity being a female thread. Said thread of the tail may be located on the outer wall of said deformable element, or under said deformable element. According to another embodiment: - said tail comprises a cavity at its end, - said raised portion of the actuator comprises said deformable element, - said punch is located in said cavity and - said screw pitch of the tail is a female thread and said screw pitch of said raised portion is a male thread. According to another embodiment, said actuator comprises a sleeve provided with a male screw pitch, said tail ends with a hollow portion defining a housing with an inlet for receiving said sleeve, and said deformable means by screwing the tail comprise a nut fixed to said inlet of said housing, said nut comprising a female thread intended to receive said male screw pitch of said sleeve, said nut comprising means for braking the screwing of said screw threads one with the 'other. Said braking means may be constituted by a ring integrated in said nut (nylon ring for example) or ovalization of said nut or a modification of a portion of one of said threads. According to another embodiment, said actuator comprises a cylindrical portion with a male screw pitch and a recess in which is inserted an elastic ring, said tail ends with a hollow portion defining a housing with an inlet provided with a chamfer and intended to receive said cylindrical portion, said housing comprising a female screw thread intended to receive said male screw pitch of said cylindrical portion and a groove in which said elastic ring can be relaxed when said tail is screwed to said portion cylindrical. Said groove may be located in said screw thread of said housing. According to an alternative embodiment, said tail ends with a tip provided with a male thread and a groove in which is inserted an elastic ring and said actuator comprises a cavity provided with a screw thread female and a recess in which said elastic ring can relax when said tail is screwed into said cavity. The inlet of said cavity, through which said tip penetrates, may advantageously comprise a chamfer on which said elastic ring is compressed when said tail is screwed into said end piece. Said clearance may be located in said female screw pitch or between said chamfer and said female screw pitch. Said cavity may be provided with a stop made of a deformable material. [00018] Said tail may be provided with at least one cavity to facilitate the screwing of said tail to said actuator, said cavity being able to be located between the valve head and said tail, or just above said valve head. Other features and advantages of the invention will become apparent from the following description of several embodiments of the invention, given by way of non-limiting example, with reference to the accompanying drawings and in which: - Figures 1a and 1b illustrate a valve "cameless" with its electromagnetic actuator; Figures 2, 3 and 5 schematically show embodiments using a punch; - Figure 4 illustrates the location of a cavity facilitating the screwing of the valve; - Figure 6 shows schematically an embodiment using a nut with braking means; - Figure 7 is a sectional view along A-A of Figure 6; - Figure 8 illustrates another location of a cavity facilitating the screwing of the valve; and - Figures 9 to 12 schematically show embodiments using an elastic ring. A fastening device according to the invention comprises means for screwing the tail of a valve to an actuator and deformable means, by screwing the valve stem. Deformation of said means makes disassembly of the valve irreversible, that is to say, unmountable without breaking an element. In addition, the mounting of the valve can be performed axially, that is to say in the direction of the longitudinal axis of the valve. Figure 2 shows schematically a device according to the invention for fixing the tail 20 of a valve 21 to the movable portion of an actuator 22. The valve 21 has a longitudinal axis 23. The valve stem ends with a deformable element 24 having the shape of a cylinder those whose external wall comprises a male screw pitch 25. The actuator 22 comprises a raised portion 30 provided with a cavity 26 intended to receive the deformable element 24. The cavity 26 is provided with a female thread 27 which cooperates with the thread 25, thus allowing the deformable element 24 to be screwed to the actuator 22. The cavity 26 is provided with a deformation member, under the shape of a punch 28, and a holding member of the deformable element 24 when the latter has been deformed, said holding element taking the form of a groove 29 located in the cavity above the pitch of The upper end of the element 24 is beveled is to facilitate the penetration of the element 24 into the cavity 26. To attach the valve to the actuator, the valve is moved along its longitudinal axis 23 and screwed into the cavity. When the punch 28 enters the element 24, the walls of this element are deformed, being spaced apart or widened until the edges of the deformable element are engaged in the groove 29. The dimensions of the deformable element and the punch are adjusted to obtain said deformation and engagement in said groove. The deformation of the element 24 is permanent. The tail 20 is then a prisoner of the actuator 22, the disassembly of the valve being impossible without damaging, or even breaking, the deformable element 24 and / or the threads 25 and 27. [00023] FIG. variant embodiment of Figure 2 according to which the male thread 25 is located under the deformable element 24. This embodiment allows easy control of the geometry of the deformable element 24, in order to improve the control of the deformation of the element 24. [00024] In order to facilitate the screwing of the valve to the actuator, it may be useful to incorporate in the valve stem means for facilitating said screwing. In FIG. 4, these means consist of a cavity 40 which can take for example the external shape of a nut (for example a hexagon nut). The impression is located just above the head 41 of the valve. FIG. 5 represents an embodiment of the invention that differs from the embodiment of FIG. 2 in that the deformation member, here a punch, is integrated with the valve stem and not with the actuator, the deformable element then being integral with the actuator. In Figure 5, the valve comprises a head 50, a rod 51 and a tail 52. The latter ends with a hollow portion generally having the shape of a hollow cylinder and defining a cavity 53. The inner wall of the cavity 3 is provided with a female thread 54. The bottom of the cavity 53 comprises a punch 55 surrounded by the holding member, a groove 56. The movable portion of the actuator 57 has a raised portion 58 whose wall external is provided with a male thread 59 intended to cooperate with the thread 54.

The end of the raised portion 58 is deformable, thereby constituting a deformable member 60. The valve is secured to the movable portion of the actuator by moving the valve toward the actuator in the direction of the longitudinal axis 61 of the actuator. the valve and by screwing the screw thread 59 in the thread 54. When the walls of the deformable element 60 come into contact with the punch 55, they deform and engage in the throat 56 which makes them prisoners . The fixation is then irreversible. [00026] FIG. 6 schematically shows another embodiment relating to a valve provided with a head 60, a rod 61 and a hollow shank 62. The inside of the shank forms a housing 63 having an inlet 64. The latter comprises a nut-shaped piece 65 provided with a female screw thread 66. The movable portion of the actuator 67 comprises a sleeve 68, whose shape is that generally of a cylinder. The outer wall of the cylinder is provided with a male screw pitch 69 intended to cooperate with the female thread 66. Braking means are integrated with the nut 65. These means may consist for example of a slight ovality. of the nut or by a modification of the thread at the end of the stroke or by a ring, for example made of nylon, integrated in the nut. To attach the valve to the actuator, the valve is moved axially toward the actuator, parallel to the longitudinal axis of the valve. The sleeve 68 is then screwed into the nut 65 until the rotation of the valve becomes difficult because of the braking means. Figure 7, which is a section along AA of Figure 6, shows the nut 65 having a ring 70 of a material, such as nylon, which slows the rotation of the valve stem in the thread 69 of the actuator. Figure 8 schematically shows a footprint 80, in the form of the outer wall of a hex bolt. This footprint, which facilitates the screwing of the valve, is located between the tail 81 and the rod 82 of the valve. As previously indicated with reference to FIG. 4, the impression can also be located just above the valve head. Figures 9 to 12 show schematically embodiments using an elastic ring. In Figure 9, the movable portion of an actuator 90 has a cylindrical portion 91comprenant cavity 92 of substantially cylindrical shape. The wall of the cavity 92 is provided with a female thread 93 in which there is a clearance 94. The cavity 92 has an inlet 95 with a chamfer 96. The tail 97 of a valve forms a tip 98 having the shape a cylinder whose outer wall comprises a male screw pitch 99, intended to cooperate with the thread 93, and a groove 100 in which is inserted an elastic ring 101. This elastic ring 101 can be relaxed, as shown in FIG. Figure 10, when not forced. The chamfer 96 facilitates the insertion of the tip 98 into the cavity 92, compressing the elastic ring 101. The tail is then screwed into the thread 93 until the elastic ring reaches the clearance 94 and engages in said release. The valve is then fixed to the actuator irreversibly. To disengage the tail of the actuator, it would break for example the elastic ring. FIG. 11 represents an embodiment identical to that of FIG. 9, with the exception of the clearance 94 which in the case of FIG. 11 is situated at the entrance to the cavity 92, before the screw thread 93. In addition, the bottom of the cavity 92 comprises a flexible stop 102 which makes it possible to obtain an adjustment of the tail of uncertain type between the end of the valve stem and the elastic ring 101, thus limiting the clearances. The stop 102 may be made for example of aluminum or copper or elastomer. Figure 12 schematically shows another embodiment using an elastic ring as in the previous embodiment. The movable portion of the actuator comprises a cylindrical portion 120 provided with a male screw pitch 121 and a recess 122 in which is placed an elastic ring 123. The valve stem 124 has at its end a hollow portion 125 forming a housing 126 whose wall comprises a female screw thread 127 intended to cooperate with the male screw pitch 121. The female screw thread 127 is provided with a groove 128.

The inlet 129 of the housing includes a chamfer 130 to facilitate insertion of the cylindrical portion 120 into the housing 126, compressing the resilient ring 123. To secure the valve to the actuator, the screw thread 127 is screwed in the screw thread 121 until the elastic ring 123 is engaged in the groove 128. The fixing of the valve is then irreversible. The present invention can be used for valves of the electromagnetic type, in particular for fixing the electromagnetic valves of a heat engine that can be hybrid. 15 20 25

Claims (10)

REVENDICATIONS1. Device for irreversibly fixing a valve stem (20) to an actuator (22), characterized in that it comprises means (25, 27) for screwing said tail to said actuator and deformable means (24) by screwing said tail, the deformation of said means being irreversible, thus making the attachment of said tail to said actuator indemountable. 2. Device according to claim 1, characterized in that said deformable means comprise a deformable element (24), a deformation member (28) of said member and a holding member (29) of said deformable member for holding said element after its deformation. . 3. Device according to claim 2, characterized in that said actuator comprises a raised portion (30) for receiving the end of said tail, in that said deformable element (24) is hollow, in that said means for screwing said tail to said actuator comprise a thread (25) belonging to said tail and a thread (27) belonging to said raised part, said threads being intended to cooperate with each other, in that that said deformation member comprises a punch (28) and in that said holding member comprises a groove (29), said punch spreading the walls of said deformable element into said groove when said tail is screwed to said actuator. 4. Device according to the preceding claim, characterized in that said deformable element (24) is located at the end of said tail, in that said element in relief comprises a cavity (26), in that said punch (28) is located at the bottom of said cavity (26), in that said groove (29) is located in said cavity and in that the thread (25) of said shank is a male thread, the thread ( 27) of said cavity being a female thread. 5. Device according to claim 3, characterized in that said tail comprises a cavity (53) at its end, in that said raised portion (58) comprises said deformable element (60), in that said punch (55) is located in said cavity (53) and in that said thread pitch (54) of the tail is a female thread and said thread pitch (59) of said raised portion is a male thread pitch. 6. Device according to claim 1, characterized in that said actuator (67) comprises a sleeve (68) provided with a male screw pitch (69), in that said tail (62) ends with a hollow portion defining a housing (63) with an inlet (64) for receiving said sleeve, and in that said tail-deformable means comprise a nut (65) fixed to said inlet of said housing and comprising a female thread (66) ) for receiving said male screw pitch (69) of said sleeve, said nut comprising means for braking the screwing of said screw threads with each other. 7. Device according to claim 1, characterized in that said actuator comprises a cylindrical portion (120) with a male screw pitch (121) and a recess (122) in which is inserted an elastic ring (123), in that said tail ends with a hollow portion defining a housing (126) with an inlet (129) provided with a chamfer (130) and intended to receive said cylindrical portion, said housing comprising a female thread (127) intended to receive said male screw pitch (121) of said cylindrical portion and a groove (128) in which said resilient ring (123) can be relaxed when said tail is screwed to said cylindrical portion. 8. Device according to claim 1, characterized in that said tail ends with a tip (98) provided with a male thread (99) and a groove (100) in which is inserted an elastic ring (101). ) and in that said actuator comprises a cavity (92) provided with a female thread (93) and a recess (94) in which said elastic ring can relax when said tail is screwed into said cavity. 9. Device according to the preceding claim, characterized in that the inlet of said cavity (95), through which said tip, comprises a chamfer (96) on which is compressed said elastic ring (101) when said tail is screwed into said tip. 10. Device according to one of the preceding claims characterized in that said tail is provided with at least one cavity (40, 80) to facilitate the screwing of said tail to said actuator.